The present invention relates generally to fiber optic cables and, more particularly, to fiber optic cables having at least one strength member.
Fiber optic cables have traditionally served as trunk cables for transmitting voice and data over relatively long distances. Since optical fibers transmit voice and data with relatively low losses and at high speed in comparison to transmission via electrical cables, fiber optic cables continue to be a preferred choice for trunk cables. For at least the same reasons, an increasing emphasis is also being placed upon extending fiber optic cables to the home or business. Thus, in addition to fiber optic cables serving as trunk cables for the transmission of voice and data over relatively long distances, fiber optic cables have been designed as drop cables for transmission of voice and data directly to the home or business.
Traditionally, coaxial or other electrical cables have served as drop cables. Thus, signals that were transmitted across a fiber optic trunk cable would be converted into corresponding electrical signals and delivered to the home via an electrical drop cable. As will be apparent, the conversion between optical and electrical signals not only introduces at least some loss, but also requires a converter, thereby increasing the overall cost of the communication system.
In view of the foregoing, a fiber optic cable according to one aspect of the present invention includes at least one optical fiber, a strength member that surrounds the at least one optical fiber, and a jacket surrounding the strength member, wherein the strength member has a modulus of elasticity of about 20 GPa and, more preferably, a modulus of elasticity of at least 40 GPa. According to another aspect of the present invention, a fiber optic cable includes at least one optical fiber, a strength member that surrounds the at least one optical fiber, and a release layer disposed between the at least one optical fiber and the strength member to facilitate separation of the strength member from the at least one optical fiber. According to either aspect of the present invention, the fiber optic cable can be designed to be self-supporting since the strength member provides substantial tensile strength. The fiber optic cable of either aspect of the present invention can therefore be utilized in a variety of applications, including use as an aerially installed, self-supporting fiber optic drop cable.
According to another aspect of the present invention, a fiber optic cable is provided that includes at least one optical fiber, a first strength member at least partially surrounding the at least one optical fiber and a second strength member at least partially surrounding the first strength member, wherein the first and second strength members are physically distinct from one another. According to this aspect of the present invention, one or both of the first and second strength members are formed of a matrix and a plurality of fibers disposed within the matrix. However, the characteristics of the fiber optic cable can be tailored to meet the requirements of various applications since the first and second strength members can include either the same type or different types of fibers depending upon the desired characteristics of the resulting fiber optic cable. The fiber optic cable of this aspect of the present invention can therefore be designed to support relatively large tensile forces, such that the fiber optic cable can be self-supporting.